The present invention relates to a discharge chute apparatus for loading dust laden, particulate materials, such as minute grains, pellets, powder lumps, etc, in freight cars, ship holds, storage bins, etc.
Conventionally, in discharging particulate materials from a supply source into loading receptacles or the like, various methods have been employed in order to restrict the environmentally contaminating dispersal of dust particles into the air. One method is to reduce the fall distance or the discharge speed of the materials. Another method is to employ filter devices. However, the discharge rate per hour is unacceptably low in the former method, and the filter mesh becomes clogged in the latter method, whereby the discharge operation must often be for stopped for cleaning.
To obviate these drawbacks, a plurality of straight pipe sections have been coaxially and slidingly engaged with each other to form an expandable chute, at the bottom of which a flexible, skirted hood has been provided. A suction pipe is then connected to the hood to draw in the dust generated in the space between the hood and the surface of the materials being discharged. The hood is adapted to be moved upwardly in response to the increasing height of the materials by retracting the expandable chute, whereby the hood remains positioned just above the surface of the discharging materials.
However, in such an apparatus substantial quantities of dust leak out between the sliding portions of the pipe sections, and their retraction is often hampered by the dust accumulating on the sliding surfaces thereof. Further, the suction pipe is generally ineffective to prevent such escaping dust from reaching and lodging in the chute sections.